Optimization of the activated sludge anoxic reactor configuration as a means to control nutrient removal kinetically

Plósz, Benedek G.

doi:10.1016/j.watres.2007.01.007

Cited by 14 publications

(9 citation statements)

References 19 publications

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“…Overall, data during continuous-flow operation suggest an enhancement in denitrification performance in the three-stage MBBR, possibly explained based on reaction kinetics principles (Plósz, 2007), e.g.,…”

Section: Denitrificationmentioning

confidence: 91%

Reactor staging influences microbial community composition and diversity of denitrifying MBBRs- Implications on pharmaceutical removal

et al. 2018

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The subdivision of biofilm reactor in two or more stages (i.e., reactor staging) represents an option for process optimisation of biological treatment. In our previous work, we showed that the gradient of influent organic substrate availability (induced by the staging) can influence the microbial activity (i.e., denitrification and pharmaceutical biotransformation kinetics) of a denitrifying three-stage Moving Bed Biofilm Reactor (MBBR) system. However, it is unclear whether staging and thus the long-term exposure to varying organic carbon type and loading influences the microbial community structure and diversity. In this study, we investigated biofilm structure and diversity in the three-stage MBBR system (S) compared to a single-stage configuration (U) and their relationship with microbial functions. Results from 16S rRNA amplicon libraries revealed a significantly higher microbial richness in the staged MBBR (at 99% sequence similarity) compared to single-stage MBBR. A more even and diverse microbial community was selected in the last stage of S (S3), likely due to exposure to carbon limitation during continuous-flow operation. A core of OTUs was shared in both systems, consisting of Burkholderiales, Xanthomonadales, Flavobacteriales and Sphingobacteriales, while MBBR staging selected for specific taxa (i.e., Candidate division WS6 and Deinococcales). Results from quantitative PCR (qPCR) showed that S3 exhibited the lowest abundance of 16S rRNA but the highest abundance of atypical nosZ, suggesting a selection of microbes with more diverse N-metabolism (i.e., incomplete denitrifiers) in the stage exposed to the lowest carbon availability. A positive correlation (p < 0.05) was observed between removal rate constants of several pharmaceuticals with abundance of relevant denitrifying genes, but not with biodiversity. Despite the previously suggested positive relationship between microbial diversity and functionality in macrobial and microbial ecosystems, this was not observed in the current study, indicating a need to further investigate structure-function relationships for denitrifying systems.

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Section: Denitrificationmentioning

confidence: 91%

Reactor staging influences microbial community composition and diversity of denitrifying MBBRs- Implications on pharmaceutical removal

et al. 2018

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“…Among the plethora of evaluated options, staging of biological reactors (defined as the subdivision into two or more completely mixed sub-reactors in series) has been proposed to optimize pollutant removal processes based on reaction kinetic principles (Scuras et al, 2001;Joss et al, 2006;Grady et al, 2011). Staging of pre-denitrifying reactors (Plósz, 2007;Plósz et al, 2010a) was accordingly hypothesized to enhance denitrification as compared to singlestage configurations. In staged systems with prolonged physical biomass retention (i.e.…”

Section: Introductionmentioning

confidence: 99%

Removal of pharmaceuticals in pre-denitrifying MBBR – Influence of organic substrate availability in single- and three-stage configurations

et al. 2017

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Due to the limited efficiency of conventional biological treatment, innovative solutions are being explored to improve the removal of trace organic chemicals in wastewater. Controlling biomass exposure to growth substrate represents an appealing option for process optimization, as substrate availability likely impacts microbial activity, hence organic trace chemical removal. This study investigated the elimination of pharmaceuticals in pre-denitrifying moving bed biofilm reactors (MBBRs), where biofilm exposure to different organic substrate loading and composition was controlled by reactor staging. A three-stage MBBR and a single-stage reference MBBR (with the same operating volume and filling ratio) were operated under continuous-flow conditions (18 months). Two sets of batch experiments (day 100 and 471) were performed to quantify and compare pharmaceutical removal and denitrification kinetics in the different MBBRs. Experimental results revealed the possible influence of retransformation (e.g., from conjugated metabolites) and enantioselectivity on the removal of selected pharmaceuticals. In the second set of experiments, specific trends in denitrification and biotransformation kinetics were observed, with highest and lowest rates/rate constants in the first (S1) and the last (S3) staged sub-reactors, respectively. These observations were confirmed by removal efficiency data obtained during continuous-flow operation, with limited removal (<10%) of recalcitrant pharmaceuticals and highest removal in S1 within the three-stage MBBR. Notably, biotransformation rate constants obtained for non-recalcitrant pharmaceuticals correlated with mean specific denitrification rates, maximum specific growth rates and observed growth yield values. Overall, these findings suggest that: (i) the long-term exposure to tiered substrate accessibility in the three-stage configuration shaped the denitrification and biotransformation capacity of biofilms, with significant reduction under substrate limitation; (ii) biotransformation of pharmaceuticals may have occurred as a result of cometabolism by heterotrophic denitrifying bacteria.

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“…Treatment is achieved naturally selected anaerobic biota in the form of anaerobic digestion without application of oxygen or mechanical mixing. In addition, anaerobic digestion could be achieved by separation between HRT (hydraulic retention time) and SRT (solid retention time), that allow anaerobic microbes to remain within the reactor independently from the wastewater flow (Plósz, 2007). Although organic material and suspended solids are efficiently removed by ABR, the process has no or very little effect on nutrients (nitrogen and phosphorus) and pathogens removal (Nasr et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Seasonal Performance and Characteristic of Abr for Low Strength Wastewater

Abbasi¹

2017

Appl Ecol Env Res

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Abstract. The performance and the characteristics of a laboratory-scale ABR (anaerobic baffled reactor) were investigated during different seasons (summer, spring, autumn and winter). ABR successfully achieved COD removal efficiencies 74% during summer, 68% during autumn/spring and 62% during winter. Compartment I, II and III showed high removal rate of COD during whole study period. At lower OLR (organic loading rate), COD removal rate was high. The analysis of biogas production during all seasons showed downward trend with increase of HRTs (hydraulic retention time). Compartment I showed high VFA (volatile fatty acid) synthesis compared to others compartments. The ABR has the potential to provide a greater efficiency and be applicable for all type of seasons and temperature conditions.

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Optimization of the activated sludge anoxic reactor configuration as a means to control nutrient removal kinetically

Cited by 14 publications

References 19 publications

Reactor staging influences microbial community composition and diversity of denitrifying MBBRs- Implications on pharmaceutical removal

Reactor staging influences microbial community composition and diversity of denitrifying MBBRs- Implications on pharmaceutical removal

Removal of pharmaceuticals in pre-denitrifying MBBR – Influence of organic substrate availability in single- and three-stage configurations

Seasonal Performance and Characteristic of Abr for Low Strength Wastewater

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